// Copyright (c) 2016-2019 Uber Technologies, Inc.
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
//	http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.
package diskspaceutil

import (
	"syscall"
)

const path = "/"

// Disk size and usage info
type UsageInfo struct {
	Util       int
	TotalBytes uint64
	UsedBytes  uint64
	FreeBytes  uint64
}

// Get disk size and usage info.
func Usage() (UsageInfo, error) {
	fs := syscall.Statfs_t{}
	err := syscall.Statfs(path, &fs)
	if err != nil {
		return UsageInfo{}, err
	}

	diskAll := fs.Blocks * uint64(fs.Bsize)
	diskFree := fs.Bfree * uint64(fs.Bsize)
	diskUsed := diskAll - diskFree
	util := int(diskUsed * 100 / diskAll)
	return UsageInfo{
		Util:       util,
		TotalBytes: diskAll,
		FreeBytes:  diskFree,
		UsedBytes:  diskUsed,
	}, nil
}
